The so called soft-shelled luggage having the luggage casing made of flexible sheet material such as a suitable fabric, plastic, or the like has been favored because of its light weight and low cost. In order to keep the dimensional stability and shape retainability, the soft-shelled luggage is generally supported by a metal framework. However, such luggage is subjected to rough handling and the abovesaid metal-framed soft-shelled luggage often fails to withstand impacts, crushings and the like. Many improvements have been disclosed, yet most of them increase substantially the overall weight of the luggage in concern.